Please tell me why I could not use "idea" in this sentence. Thanks!

Welcome to the forum Starto!
Well you must know that pronoun and verb should agree with the subject .

"As you preview the material, you get some ideas of the content and how it is organized. "

Here in the clause [you get some ideas of the content and how it is organized], the pronoun "it" and the verb "is" are wrong because [it] is referring to ideas which is plural so u

hmm - I'm not convinced by that argumetn - people DO say what "the author" origninally wrote - presumably because "you get some idea" is an idiomatic phrase?

"Some idea" unifies all your reflections into an overall sense or gestalt of what the author is of the text you're studying is doing.

You could also say that you get, or more usually, were able to come up with some ideas, that is, some separate thoughts, ABOUT (not of) "the content and how it is organized"

As you preview the material, you may come up with some ideas about

QUOTE "...the pronoun "it" and the verb "is" are wrong because [it] is referring to ideas..."

No. The pronoun "it" is referring to the content.

"...you get some idea(s) of the content and how the content is organized."

I agree with Bratannia; the singular is better. "...you get some idea of the content and how it is organized"

In that sentence, "idea" is used as an uncountable noun meaning "knowledge" or "understanding, and it is correct to use it with "of".

If "some ideas" had been used, instead of "some idea", the meaning of the sentence would be different.

And it is also true that "it" refers to the content.

'to get some idea of' means 'come to understand'. In this common verb phrase, the word 'idea' is usually used in an uncountable or 'mass' sense. Consequently, one perfectly acceptable version would be:

As you preview the material, you get some idea of its contents and how it is organised.

The 'it' in the last verb phrase is obviously referrig to 'the material.' However, i